The present invention relates generally to marine propulsion systems, and more particularly, to a reverse gate for a twin jet drive marine propulsion system.
Marine vessels can be equipped with a variety of propulsion systems. One such system is a water jet. A water jet system intakes water from a body of water and propels it from a generally aft position of the vessel. The propulsion of water provides the motive force to the watercraft. Water jet systems generally include an engine, a stationary nozzle, an impeller, a steering nozzle, and some form of a reverse gate. A twin jet drive system generally includes two such systems.
The steering nozzle is generally pivotably attached to the  stationary nozzle or a fixed portion of the watercraft and provides directional discharge therefrom. The directional discharge is controlled by an operator and facilitates steering of the vessel when the vessel is operated in a forward direction. A reverse gate is generally pivotally attached to the steering nozzle and rotates relative thereto. Reverse gates typically redirect water from the steering nozzle in a downward and forward direction.
The forward discharge of water from the reverse gate provides a neutral and/or reverse thrust to the watercraft. When a forward direction of travel is desired, the reverse gate is generally positioned in an inoperative position. The inoperative position is generally defined as having the reverse gate removed from the discharge flow of the steering nozzle. When a reverse or neutral direction of travel is desired, the reverse gate is rotated to redirect the flow from the steering nozzle either under the vessel or into a vertical plane. Neutral direction of travel is achieved by redirecting a portion of the flow discharged from the steering nozzle such that the reverse gate generates a reverse thrust that is substantially similar to the forward thrust generated by the portion of the flow not redirected by the reverse gate. Reverse is achieved by rotating the  reverse gate further into the discharge flow from the steering nozzle so that the net thrust is in the reverse direction. Such redirection of flow from the steering nozzle effectively slows and/or reverses the direction of travel of the watercraft.
Steering of the watercraft, when in reverse or neutral, is accomplished by rotation of the steering nozzle with the reverse gate attached thereto. Such a construction requires complex linkage mechanisms to accommodate the two planes of rotation of the reverse gate relative to the watercraft. Additionally, having the steering nozzle and the reverse gate attached to one another requires that the reverse gate be removed in order to remove the steering nozzle from the vessel. Reverse gates that redirect the discharge from the steering nozzle under the vessel, or in a vertical direction, are also inefficient for steering of the watercraft when in the reverse or neutral travel directions. These systems may be advantageous to stopping a watercraft, however, they are inefficient for steering of the vessel in reverse directions.
Reverse gates are typically designed for operation in watercraft with single jets and are not optimized for twin jet installations. Particularly, in twin jet watercraft equipped  with reverse gates that are secured thereto independent of the steering nozzle, a significant portion of the flow is not used effectively. That is, there can be an interference between the inboard portion of the reverse flow and the transom of the boat. This interference also creates inefficiencies in the neutral and reverse operating conditions of a watercraft so equipped.
It would therefore be desirable to design a system and method capable of providing a reverse gate for a twin jet watercraft so that the reverse gate is secured thereto independent of the steering nozzle and wherein the reverse gate provides both improved reverse thrust and steering for reverse operation of the watercraft.